Agricultural combines are heavy large machines that harvest, thresh, separate and clean harvested crop, planted agriculturally that carries corn. They include steerable rear wheels mounted on the free ends of rear axles that pivot about a central longitudinal axis.
The axles are telescopic and can be varied in length by stopping the vehicle, loosening clamps and forcing the extendible axle member in (or out) of an outer axle member until a desired axle length is achieved, then tightening short axle clamps to lock the extensible axle member and the outer axle member in that position.
In new harvesters, it has been proposed to permit the extendible axle of the combine to slide in and out of the outer axle while the vehicle is being driven through a field. Hydraulic actuators have been considered for use to extend the axles during operation. In this arrangement the extendible axle member and outer axle member may be provided with a releasable clamp that can be opened when the axles are telescoped and then reapplied when the axle has the desired length.
Axles that can be extended and retracted while the agricultural combine is under way performing its harvesting functions will require improved axles with tighter tolerances. In addition, other activities typically performed by the operator when manually extending and retracting the axle will have to be performed automatically or eliminated.
One such function is insuring that the inner telescopic axle member is clean before retracting it into the outer telescopic axle member to prevent jamming, corrosion, or undue wear.
U.S. Pat. No. 5,121,808 shows a telescoping steering axle with a non driven (gauge) wheel supported on an inner axle member. The inner axle slides loosely into the outer axle and is clamped against one side of the outer axle by bolts that pass through the inner and outer axle. The bolts are located at the outer end of the outer tube and the inner tube is unsupported. See the cutaway in FIG. 1.
U.S. Pat. No. 5,464,243 shows an extendible axle for a self-propelled sprayer having an outer axle and an inner axle. A clamping arrangement in the form of a V-shaped wedge with plastic shims on top is provided at the bottom of the outer end of the outer tube. The inner end of the inner axle tube is unsupported. Bolts in the bottom of the outer tube are provided to abut the wedge and force it up against the inner tube, lifting the inner tube and wedging in against a plastic shim at the top of the outer tube. The bolts are tightened to lock the inner tube in position with the new preferred row spacing
U.S. Pat. No. 5,489,114 shows a telescopic axle assembly for an aerial work platform having wheels that are telescopically extended to increase the wheelbase and make the vehicle more stable when the vehicle is stopped and the aerial work platform is being used. The axle is constructed of three nested telescopic member, a central hollow square tubular member fixed to the chassis and two hollow square tubular members in which each of the three members is telescoped inside the other. Bearing strips of undetermined shape are located between the top and side walls of the three members to facilitate the extension and contraction of the tubular members.